System and method for supporting antenna beamforming in a cellular network

ABSTRACT

The present invention is a method and system for supporting a beamforming antenna system in a mobile broadband communication network with an improved beam pattern, beam sweep pattern, pilot channel design with feedback and reporting rules, and control signaling design. Specifically, the improved beam pattern includes a method of supporting wireless communications in a wireless network forming at least two spatial beams within a cell segment where the at least two spatial beams are associated with different power levels, and separately, where at least two spatial beams can be moved across the cell segment according to a unique sweep pattern. The pilot channel design improves network bandwidth performance and improves user mobility tracking. Feedback and reporting rules can be established using a particular field designator, CQI, in the preferred embodiment.

RELATED APPLICATION DATA

This application is a continuation of U.S. patent application Ser. No.16/289,783, filed on Mar. 1, 2019, which is a continuation of U.S.patent application Ser. No. 15/969,108 filed on May 2, 2018 (now U.S.Pat. No. 10,263,683), which is a continuation of U.S. patent applicationSer. No. 15′/590,151 filed on May 9, 2017 (now U.S. Pat. No. 9,985,710),which is a continuation of U.S. patent application Ser. No. 14/289,723filed on May 29, 2014 (now U.S. Pat. No. 9,680,536), which is acontinuation of U.S. patent application Ser. No. 12/990,989 filed onNov. 4, 2010 (now U.S. Pat. No. 8,750,933), which claims the benefit ofand is a National Phase Entry of International Application No.PCT/US2009/002866, filed on May 8, 2009, which claims the benefit ofProvisional Patent Application Ser. No. 61/052,011 filed on May 9, 2008,which are hereby incorporated by reference into this utility patentapplication.

TECHNICAL FIELD OF THE INVENTION

The claims in the instant application are different than those of theparent application or other related applications. The Applicanttherefore rescinds any disclaimer of claim scope made in the parentapplication or any predecessor application in relation to the instantapplication. The Examiner is therefore advised that any such previousdisclaimer and the cited references that it was made to avoid, may needto be revisited. Further, any disclaimer made in the instant applicationshould not be read into or against the parent application or otherrelated applications.

BACKGROUND OF THE INVENTION

There is an increasing demand on mobile wireless operators to providevoice and high-speed data services, and at the same time, theseoperators want to support more users per basestation to reduce overallnetwork costs and make the services affordable to subscribers. As aresult, wireless systems that enable higher data rates and highercapacities are needed. The available spectrum for wireless services islimited, however, and the prior attempts to increase traffic within afixed bandwidth have increased interference in the system and degradedsignal quality.

Wireless communications networks are typically divided into cells, witheach of the cells further divided into cell sectors. A base station isprovided in each cell to enable wireless communications with mobilestations located within the cell. One problem exists when prior artomni-directional antennas are used at the basestation because thetransmission/reception of each user's signal becomes a source ofinterference to other users located in the same cell location on thenetwork, making the overall system interference limited. Such anomni-directional antenna is shown in FIG. 1(a).

In these traditional omni-directional antenna cellular network systems,the base station has no information on the position of the mobile unitswithin the cell and radiates the signal in all directions within thecell in order to provide radio coverage. This results in wasting poweron transmissions when there are no mobile units to reach, in addition tocausing interference for adjacent cells using the same frequency, socalled co-channel cells. Likewise, in reception, the antenna receivessignals coming from all directions including noise and interference.

An effective way to increase efficiency of bandwidth usage and reducethis type of interference is to use multiple input-multiple output(MIMO) technology that supports multiple antennas at the transmitter andreceiver. For a multiple antenna broadcast channel, such as the downlinkon a cellular network, transmit/receive strategies have been developedto maximize the downlink throughput by splitting up the cell intomultiple sectors and using sectorized antennas to simultaneouslycommunicate with multiple users. Such sectorized antenna technologyoffers a significantly improved solution to reduce interference levelsand improve the system capacity.

The sectorized antenna system is characterized by a centralizedtransmitter (cell site/tower) that simultaneously communicates withmultiple receivers (user equipment, cell phone, etc.) that are involvedin the communication session. With this technology, each user's signalis transmitted and received by the basestation only in the direction ofthat particular user. This allows the system to significantly reduce theoverall interference in the system. A sectorized antenna system, asshown in FIG. 1(b), consists of an array of antennas that directdifferent transmission/reception beams toward users located in thecoverage area of the sector of the cell.

To improve the performance of a sectorized cell sector, schemes havebeen implemented using orthogonal frequency domain multiple access(OFDMA) systems, which are also called Space-Division Multiple Access(SDMA) systems. In these systems, mobile stations can communicate withthe base station using one or more of these spatial beams. This methodof orthogonally directing transmissions and reception of signals, calledbeamforming, is made possible through advanced signal processing at thebase station.

A beamforming scheme is defined by the formation of multiple spatialbeams within a cell sector to divide the cell sector into differentcoverage areas. The radiation pattern of the base station, both intransmission and reception, is adapted to each user to obtain highestgain in the direction of that user. By using sectorized antennatechnology and by leveraging the spatial location and channelcharacteristics of mobile units within the cell, communicationtechniques called space-division multiple access (SDMA) have beendeveloped for enhancing performance. Space-Division Multiple Access(SDMA) techniques essentially creates multiple, uncorrelated spatialpipes transmitting simultaneously through beamforming and/or precoding,by which it is able to offer superior performance in multiple accessradio communication systems.

One type of beamforming scheme is an adaptive beamforming scheme thatdynamically directs beams toward a location of a mobile station. Such anadaptive beamforming scheme requires mobility tracking in whichlocations and spatial characteristics of mobile stations are tracked forthe purpose of producing the adaptive beams. Depending on location andspatial characteristics, each user's signal is multiplied by complexweightings that adjust the magnitude and phase of the signal to and fromeach antenna. This causes the output from the array of sectorizedantennas to form a transmit/receive beam in the desired direction andminimizes the output in other directions, which can be seen graphicallyin FIG. 2.

However, the mobility and spatial channel tracking of the user'slocation in the network cell required by these beamforming antennasystems increases the overhead of the system. Moreover, mobility andspatial channel tracking may not be possible or practical with mobilestations moving at relatively high velocities. There is a need forsupport of sectorized beamforming antenna systems in mobile broadbandcommunication networks, including solving some of the above-identifiedproblems.

The various components on the system may be called different namesdepending on the nomenclature used on any particular networkconfiguration or communication system. For instance, “user equipment”encompasses PC's on a cabled network, as well as other types ofequipment coupled by wireless connectivity directly to the cellularnetwork as can be experienced by various makes and models of mobileterminals (“cell phones”) having various features and functionality,such as Internet access, e-mail, messaging services, and the like.

Further, the words “receiver” and “transmitter” may be referred to as“access point” (AP), “basestation,” and “user” depending on whichdirection the communication is being transmitted and received. Forexample, an access point AP or a basestaion (eNodeB or eNB) is thetransmitter and a user is the receiver for downlink environments,whereas an access point AP or a basestaion (eNodeB or eNB) is thereceiver and a user is the transmitter for uplink environments. Theseterms (such as transmitter or receiver) are not meant to berestrictively defined, but could include various mobile communicationunits or transmission devices located on the network.

SUMMARY OF THE INVENTION

The present invention is a method and system for supporting abeamforming antenna system in a mobile broadband communication networkwith an improved beam pattern, beam sweep pattern, pilot channel designwith feedback and reporting rules, and control signaling design.Specifically, the improved beam pattern includes a method of supportingwireless communications in a wireless network forming at least twospatial beams within a cell segment where the at least two spatial beamsare associated with different power levels, and separately, where atleast two spatial beams can be moved across the cell segment accordingto a unique sweep pattern.

The pilot channel signaling design improves network bandwidthperformance and improves the tracking of user channel characteristics,mobility, and location. Feedback and reporting rules can be establishedusing a particular field designator, CQI, in the preferred embodiment.Further, a control signaling design is proposed in the present inventionto improve network bandwidth performance and improve the tracking ofuser channel characteristics, mobility, and location, which uses theforward link (downlink) control signal, FL, in the preferred embodiment.These pilot channel and control signaling designs assist the system inanalyzing which directional transmission beam is best suited for thetransmission to the user equipment or when the directional transmissionbeam should be activated. The present invention solves problemsassociated with tracking user equipment spatial channel characteristics,mobility or location, improve bandwidth and coverage performance of thenetwork, and reduce overhead transmissions of the network.

BRIEF DESCRIPTION OF THE DRAWINGS

The objects and features of the invention will become more readilyunderstood from the following detailed description and appended claimswhen read in conjunction with the accompanying drawings in which likenumerals represent like elements and in which:

FIG. 1 is a graphical illustration of an omni-directional antenna (a)and a sectorized antenna (b);

FIG. 2 is a graphical illustration of a weighted sectorized transmissionbeam directed to the desired user;

FIG. 3 illustrates an exemplary cell that is associated with a basestation that is capable of forming spatial beams having different powerlevels that are moved according to a sweep pattern, in accordance with apreferred embodiment;

FIG. 4 illustrates spatial beams associated with different beampositions that are formed within a cell sector, in accordance with apreferred embodiment;

FIGS. 5A-5F illustrate sweep patterns of the spatial beams, inaccordance with an embodiment;

FIGS. 6-7 illustrate different beam configurations, in accordance withsome preferred embodiments;

FIG. 8 illustrates spatial beams formed in different cell sectors, inaccordance with a preferred embodiment;

FIG. 9 is a front view of an antenna structure of a base station thathas two antenna panels, where each antenna panel has antenna elementscapable of forming spatial beams according to some preferredembodiments;

FIG. 10 is a side view of the antenna structure of FIG. 9;

FIG. 11 illustrates a first configuration of spatial beams generated intwo different cells, in accordance with an embodiment;

FIG. 12 illustrates a second configuration of spatial beams generated intwo cells, according to another embodiment;

FIGS. 13 and 14 illustrate different techniques of communicating controland data signaling, in accordance with some preferred embodiments;

FIGS. 15 and 16 illustrate frame structures for communicating data,according to some preferred embodiments;

FIG. 17 is a block diagram of exemplary components of a base station andmobile station; and,

FIG. 18 is a diagram showing the PHY frames and the pilot indicatorchannel signal.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In FIG. 1(a), the overall transmission architecture 100 of anomni-directional antenna 105 that transmits radially outward equally invarious directions shown by arrows 125, 115, 135 and 140. The perimeterof the coverage area is shown by the area 120 for the transmissionarchitecture 100. Improved efficiencies have been achieved by using thesectorized antenna architecture 141 shown in FIG. 1(b).

Multiple antennas 145, 147 and 148 are shown in the architecture 140,wherein each antenna is directed toward a different region of thecellular network shown by the directional transmission 175 for coveragearea 150, transmission 190 for coverage area 157, and directionaltransmission 180 for coverage area 155. In this context, it is possiblefor system capacity to be improved by the sectorized architecture.

By varying the strength of various transmission signals, additionalefficiencies and reduced interferences can be achieved as shown in FIG.2 for the sectorized architecture 200. Multiple antenna 215, 220, 227and 230 direct transmissions (or receive transmissions) in thesectorized antenna architecture 200. A directional antenna beam 235 isformed by increasing the strength of that signal from antenna element230. The desired user 205 is shown receiving a desired transmission 245in high signal strength coverage area 235, which is a higher poweredbeam meant to be directed to that user 205. An interfering user 210 isshown with lower strength transmission signal 240, which reduces theinterference encountered in the system related to that user 210.

In accordance with some preferred embodiments, an “opportunistic” spacetime multiple access (OSTMA) technique is provided for use in wirelesscommunications networks. The OSTMA technique enables the formation ofmultiple spatial beams in a cell segment (cell or cell sector), where atleast some of the multiple spatial beams of the cell segment areassociated with different power levels to provide different coverageareas within the cell segment. A spatial beam (or more simply “beam”)refers to a geographically distinct coverage region within a cellsegment in which wireless communication between a base station andmobile station(s) can be performed.

In addition, the OSTMA technique defines a sweep pattern for the beamswithin a cell segment, where the sweep pattern can be a fixed sweeppattern or a dynamic sweep pattern. A “sweep pattern” refers to a mannerin which beams within a cell segment are moved, over time, among beampositions in the cell segment. A fixed sweep pattern means that thebeams are moved among the beam positions according to a predeterminedsequence. A dynamic sweep pattern means that the beams can be movedamong the beam positions in possibly different sequences, depending uponone or more criteria. According to preferred embodiments, the beampositions across which beams are moveable are fixed beam positions—thus,although the spatial beams are moveable within the cell segment, thepositions to which such beams are moved remain fixed for a certain timeduration. It is also possible to re-configure beam positions within thesystem. (e.g. change 2 beams to 4 beams, or 8 beams, etc.).

To some preferred embodiments, the OSTMA scheme is provided for theforward wireless link from the base station to the mobile stations. Inalternative embodiments, the OSTMA scheme can also be used for thereverse wireless link from the mobile station to the base station. Thecommunication connection in which data flow from the base station to themobile station is called the forward link (FL). Likewise, thecommunication connection in which data flow from the mobile station tothe base station is called the reverse link (RL). Communicationconditions are not always the same for both the FL and the RL. Forexample, a mobile station may be communicating with a serving basestation which has a highly congestive RL traffic but a relatively openFL flow. The mobile station may need to adjust its RL connectionsbecause to stay with the same base station for both FL and the RL (if amore open RL connection is available from another base station) may notbe the best use of communication resources.

In one example, as depicted in FIG. 3, a cell 300 has three sectors300A, 300B, and 300C. Within sector 300A, a base station 302 has anantenna structure that forms multiple spatial beams, including ahigh-power beam 304 and low-power beams 306. A “high-power beam” refersto a beam in which wireless communications is performed at an elevatedtransmission power, whereas a “low-power beam” refers to a beam in whichwireless communications is performed at a transmission power less thanthe elevated transmission power.

In FIG. 3, the coverage area within the inner edge 308 is referred to asan “inner cell region,” and the ring-shaped area between the inner cellregion and the outer edge of the cell 300 is referred to as an “outercell region.” Note that the high-power beam 304 is able to provide acoverage area from the antenna structure 302 to an edge of the cell 300.On the other hand, the low-power beams 306 are able to provide coverageup to an inner edge 308 where the inner edge has a radius that issmaller than a radius associated with the outer edge of the cell 300.

The high-power beam 304 provides coverage for mobile stations located inboth the inner and outer cell regions, whereas the low-power beams 306are used to provide coverage for mobile stations located within theinner cell region (but not the outer cell region). The low power beamscan be operable at substantially similar power levels, or dissimilarpower levels, in each instance at a transmission power that is less thanthe high power level. Although just one high-power beam 304 is depicted,it is noted that multiple high-power beams 304 can be used inalternative preferred embodiments.

In the present invention, the beam pattern of simultaneous high powerand low power beams transmitted from the basestation (access node)applies to the forward link, but can be adapted to apply to the reverselink as well. The high power beam services users on the edge of the cellsite, whereas the low power beams serve the users in the center of thecell site. A “superframe” preamble may be used in conjunction with thepresent invention and transmitted omni-directionally in the sector.

Employing low-power beams 306 allows for less interference fromtransmissions in each of the cell sectors 300A, 300B, and 300C. This iscontrasted with conventional techniques in which multiple beams formedwithin a cell sector have a fixed power level, where the fixed powerlevel is high enough such that the beam can cover all the way to theedge of the cell sector. As a result, by employing multiple beams all atthe same relatively high power level, interference created in adjacentcells is increased. In contrast, using the OSTMA technique according tothe preferred embodiments in which some of the beams of a cell sectorare lower power than other beams in the cell sector, reducedinterference is achieved.

Although reference is made to providing spatial beams in a cell sectorin this description, it is noted that similar techniques can be providedfor entire cells. In accordance with some preferred embodiments, sincenot all of the spatial beams within a cell sector are able to providecoverage to mobile stations within the outer cell region, the high-powerbeam 304 can be moved to different beam positions to provide coveragefor different mobile stations located at different locations in theouter cell region.

The beams within a cell sector or cell can be non-overlapped beams (suchas depicted in FIG. 6) or overlapped beams (such as depicted in FIG. 7),In some implementations, beams are considered non-overlapped if thefollowing is true: if the 3-dB (decibel) beamwidth is x°, then the beamsare separated by about every x°, as depicted in FIG. 6. Beams areconsidered to be overlapped if the following condition is true: if the3-dB·beamwidth is x°, the beams are separated by less than somepredefined fraction (e.g., ½) of x°. FIG. 7 shows an example in whichadjacent beams are separated by x/2° separation.

FIG. 4 shows an example in which six possible beam positions areprovided. In the example of FIG. 4, the high-power beam 404 is providedin beam position 1, whereas the low-power beams 406 are provided in beampositions 2-6. Beam positions 1-6 are the fixed beam positions acrosswhich the low and high-power beams 404, 406 can be swept.

Sweeping of the beams among the six exemplary beam positions of FIG. 4is depicted in FIGS. 5A-5F. FIGS. 5A-5F show two mobile stations labeledAT1 and AT2. Mobile station AT1 is located in the outer cell region andthus within the reach of the high-power beam 404, but not the low-powerbeams 406. On the other hand, mobile station AT2 is located within theinner cell region and thus is within the coverage area of the low-powerbeams 406. At time interval 1 (FIG. 5A), the high-power beam in theexample depicted in FIGS. 5A-5F is located in beam position 1. Thelow-power beams 406 are located in beam positions 2-6.

At time interval 2 (FIG. 5B), the high-power beam 404 has moved to beamposition 2, and a low-power beam 406 is now in beam position 1. Notethat in FIG. 5B, mobile station AT1 is outside the coverage region ofthe low-power beam 406 in beam position 1. At time interval 3 in FIG.5C, the high-power beam 404 has moved to beam position 3, with alow-position beam replacing the high-power beam in beam position 2. Themovement of the high-power beam 404 and low-power beams 406 continues ineach of the successive time intervals 4, 5, and 6 (FIGS. 5D, 5E, and 5F,respectively).

The six time intervals together make up a sweep period. Within a sweepperiod, the high-power beam 404 is moveable to cover all possible beampositions. More generally, within each sweep period, any given beam ismoveable to cover all possible beam positions. The sweep pattern thenrepeats for the next beam period, with the high-power beam 404 returningto beam position 1 at time interval 7 and continuing on to time interval13 as the next interval for beam position 1. The sweep pattern depictedin FIGS. 5A-5F is an example of a fixed (or deterministic) pattern inwhich each beam rotates by one beam position with each time interval. Ina different embodiment, other patterns can be used, including othertypes of deterministic patterns or even random patterns. The high-powerbeam may also be scheduled based on cell-edge user density in each beampattern.

In an alternative embodiment, four beams can be used instead of sixbeams, with one beam being a high-power beam 404 and the remaining threebeams being low-power beams 406. An 8-interface HARQ structure would beused in this embodiment. The beam sweep pattern in this embodiment wouldstart with the high-power beam 404 being in position 1, and thelow-power beams being in positions 2, 3 and 4 at time interval 1. Attime interval 2, the high-power beam 406 would shift to position 2, withthe low-power beams being in position 1, 3 and 4. At time interval 3,the high-power beam 406 would shift to position 3, with the low-powerbeams being in position 1, 2 and 4. At time interval 4, the high-powerbeam 406 would shift to position 4, with the low-power beams being inposition 1, 2 and 3. After time interval 5, the beam pattern wouldrepeat beam position 1 for the high-power beam 406, with low-power beamsat positions 2, 3, and 4. The beam pattern would then repeat thesequence sweeping across the cell sector in that fixed beam pattern.

In an alternative embodiment, three beams can be used instead of four orsix beams, with one beam being a high-power beam 404 and the remainingtwo beams being low-power beams 406. A 6-interface HARQ structure wouldbe used in this embodiment. The beam sweep pattern in this embodimentwould start with the high-power beam 404 being in position 1, and thelow-power beams being in positions 2 and 3 at time interval 1. At timeinterval 2, the high-power beam 406 would shift to position 2, with thelow-power beams being in position 1 and 3. At time interval 3, thehigh-power beam 406 would shift to position 3, with the low-power beamsbeing in position 1 and 2. At time interval 4, the beam pattern wouldrepeat beam position 1 for the high-power beam 406, with low-power beamsat positions 2 and 3. The beam pattern would then repeat the sequencesweeping across the cell sector in that fixed beam pattern.

In alternative embodiments, instead of using a fixed sweep pattern, adynamic sweep pattern can be employed. With the dynamic sweep pattern,the movement of beams across the beam positions of a cell sector can bedynamically based on one or more of the following criteria: presence ofmobile stations within a geographic region of a cell sector, channelconditions (e.g., conditions of wireless links), quality of service(QoS) requirements of applications involved in wireless communications,loading of channels, and so forth.

For example, depending upon the one or more criteria, instead of havingthe high-power beam 404 sweep in the deterministic manner depicted inFIGS. 5A-5F, a scheduler associated with a base station can specify thatthe high-power beam remain in a particular beam position for more thanone time interval. Also, the scheduler can specify that rather than thehigh-power beam 404 progressively moving to the next beam position witheach time interval, the high-power beam can instead be moved to anothertarget beam position several positions away. Instances where it may bedesirable to move the high-power beam in this manner include instanceswhere the scheduler may have detected that mobile stations at the targetbeam position may require servicing (e.g., such mobile stations may havehigher QoS requirements that would indicate that priority should begiven to servicing such mobile stations over other mobile stations withlower QoS requirements).

In some embodiments, note that each beam can have its own sweep patternand beam duration. The base station can coordinate the multiple sweeppatterns and beam durations of the multiple beams within a cell or cellsector. The sweep pattern of beams provides for spatial variation of thebeams. In addition to providing spatial variation, some preferredembodiments also allows for time-based variation, which is defined bybeam duration (the amount of time a beam remains at a particular beamposition). Generally, the beam design according to preferred embodimentsis specified by its sweep pattern and beam duration of a beam. The sweeppattern (fixed or dynamic) is specified by a sequence of beam positionsas time evolves. The beam duration can also be fixed or dynamic.

Different cells or cell sectors can use different sets of fixed beampositions, as well as different numbers of beams that are turned onsimultaneously. The sweep patterns and/or beam durations can also differin different cells or cell sectors. The beam sweep pattern embodiments(six, four or three beams, fixed or dynamic sweep patterns, etc.) relateto single sectors on the cell site location. Other sectors may usesimilar beam pattern sweeps or high-low power beams to communicate withuser equipment located in the other sectors. The system, however, mustconsider the beam patterns and synchronous systems of the neighboringsectors to avoid high power beam collisions that may result if thesebeam patterns are not coordinated among the different sectors in thecell site location. As such, coordination between multiple base stationswould be desirable to reduce inter-cell/inter-sector interference and tosupport network-based MIMO (multiple input multiple output) (whichrefers to the ability of a transmitter that has multiple antennas tosend multiple information simultaneously for receipt by multipleantennas of a receiver).

In some embodiments, four possible configurations may be available: (1)configuration 1 (static sweep pattern and static beam duration); (2)configuration 2 (dynamic sweep pattern and dynamic beam duration); (3)configuration 3 (dynamic sweep pattern and static beam duration); and(4) configuration 4 (static sweep pattern and dynamic beam duration).

With configuration 1, where a static (fixed) sweep pattern with static(fixed) beam duration are used, one possible benefit is that lesscontrol overhead and feedback would be required. For example, with afixed sweep pattern and fixed beam duration, the time interval within asweep period can be implicitly used as a beam identifier and the mobilestation does not have to provide any feedback regarding the beamidentifier. The mobile station can also run predictive algorithms, suchas to listen to the forward link only when the mobile station expectsthe beam to sweep to its location, i.e. (discontinuous reception (DRX)).Discontinuous transmission (DTX) can be performed if there is no mobilestation within a particular coverage area of a beam. DTX refers togating applied to a transmitter to turn off a transmission.

The sequence of beam positions that describe the sweep pattern can besequential, pseudorandom, or coded in terms of beam positions. In theexample where there are five beams per cell sector, one example of asequential sweep pattern is as follows: {1, 2, 3, 4, 5, 1, 2, 3, 4, 5, .. . }. What this means is that a particular beam goes to beam position 1in a first time interval, position 2 in a second time interval, position3 in a third time interval, position 4 in a fourth time interval,position 5 in a fifth time interval, back to position 1 again in thesixth time interval, and so forth.

An example of a pseudorandom sweep pattern is as follows: {2, 5, 3, 1,4, 2, 5, 3, 1, 4 . . . }. Note that the difference between thepseudorandom sweep pattern and the sequential sweep pattern is thatwithin a sweep period of five time intervals, the sequence of the sweepdoes not progress from position 1 to position 2 to position 3 toposition 4 to position 5, but rather the sweep of a particular beam israndomized. In the example above, a beam position starts in position 2in a first time interval, proceeds to position 5 in a second timeinterval, proceeds to position 3 in a third time interval, proceeds toposition 1 in a fourth time interval, and proceeds to position 4 in afifth time interval. This sequence repeats again in the next sweepperiod. Thus, from sweep period to sweep period, the pseudorandom sweeppattern repeats the same order of pattern positions.

A coded sweep pattern refers to a sweep pattern that depends upon whichcell sector the beams are located in. Different cell sectors (associatedwith different codes) would use different sweep patterns. FIG. 8 showsan example that has multiple cells 800, 802, 804, and 806, with eachcell having three cell sectors. In the example of FIG. 8, it is assumedthat there are three beams per cell sector. The beam positions arenumbered sequentially from 1 to 3 in a counter-clockwise direction. Thesweep pattern of a cell sector in cell 806 can be: {1, 2, 3, 1, 2, 3, .. . }. The sweep pattern of a cell sector of each of cells 800 and 804can be {2, 3, 1, 2, 3, 1, . . . }, and the sweep pattern in each cellsector of cell 802 can be {3, 1, 2, 3, 1, 2, . . . }. The differentsweep patterns used in the different cells are designed to reduceinter-cell interference (interference between beams located in differentcells).

In configuration 2, where dynamic sweep pattern and dynamic timeduration are used, flexible on-demand beamforming can be provided. Forexample, a beam can be formed based on mobile station presence in acoverage area of a beam, based on the channel condition, based on QoS,and based on support of special transmission schemes, such asnetwork-based MIMO. However, although flexibility is enhanced, thecomplexity of the base station scheduler and feedback mechanism is alsoincreased to support such beamforming patterns and durations. To enabledynamic sweep pattern and dynamic beam duration, pre-flash messages(discussed further below) can be sent by the base station to allowmobiles stations to report measurements back to the base station.

The other configurations that can be employed include configuration 3,which uses dynamic sweep pattern and static beam duration, andconfiguration 4, which uses static sweep pattern and dynamic beamduration. More generally, the dynamic variation of one or morecharacteristics (e.g., 1, 5 sweep pattern and/or beam duration) can bebased on one or more of the following criteria: presence of mobilestations within a particular geographic region, channel conditions(e.g., conditions of wireless links), QoS requirements of applicationsinvolved in wireless communications, loading of channels, and so forth.Another characteristic of beams that can be varied (based on one or moreof the above-listed criteria) is beam duty cycle, which specifies theamount of time that a beam is activated, or turned on, within the beamduration. The duty cycle of a beam refers to the ratio of the time thata beam is activated (or turned “on”) versus the amount of time that abeam is deactivated (or turned “off”) for a given beam position andduring a given time interval. For example, the duty cycle of aparticular beam in beam position 1 can be 70%, which means that the beamwill be activated (or turned “on”) for 70% of the time interval anddeactivated (or turned “off”) for 30% of the time interval. The abilityto vary the duty cycle of a beam based on scheduling needs allows forlower interference levels because beams that are no longer needed can beturned off temporarily or for greater periods of time.

In accordance with some preferred embodiment, basestations are able toperform “pre-flash” to enable dynamic adjustment of one or morecharacteristics (e.g., sweep pattern, beam duration, beam duty cycle,etc.). For example, when a dynamic sweep pattern is used, a high-powerbeam may be located in a particular beam position for a relativelyextended period of time. This situation may prevent other mobilestations in the outer cell region of other beam positions from beingable to communicate with the base station for the relatively extendedperiod of time.

To address this issue, pre-flashing can be used, where pre-flashingrefers to a procedure in which a base station issues a short pilot burst(or burst of other messaging) to a particular direction. Mobile stationsin the coverage area corresponding to the particular direction can thenmake measurements of the pre-flash message and provide reports back tothe base station regarding the measurements. In one example, a mobilestation can report an indication of wireless channel quality, such as inthe form of a channel quality indication (CQI). The base station canperform pre-flashes in all directions of a particular cell sector. Usingthe measurement reports from the mobile stations, the base station isable to perform scheduling as discussed above by dynamically adjustingbeam duration, duty cycle, and beam scheduling.

Note that the pre-flashes issued by the base station and actual traffictransmissions can be time multiplexed with different periodicities(which means that the periods during which pre-flashes are transmittedcan be adjusted relative to the periods during which traffic istransmitted). For example, the pre-flashes can be issued in the middleof a lengthy download of data to a particular mobile station, with thepre-flashes done in a time multiplexed manner with the download of datato the particular mobile station.

In accordance with some embodiments, as depicted in FIG. 9, an antennastructure 900 (which is part of a base station, such as base station 302in FIG. 3) can be provided with multiple antenna assemblies, includingan upper antenna assembly 902 mounted to an antenna support 906, and alower antenna assembly 904 mounted to the antenna support. In theimplementation depicted in FIG. 9, each of the antenna assemblies 902and 904 is an antenna panel. The antenna assembly 904 is positionedbelow (in the vertical direction) the upper antenna assembly 902.

The antenna assembly 902 includes multiple antenna elements 908. Thelower antenna assembly 904 includes multiple antenna elements 910. Theantenna elements 908 and 910 can cooperate to form the beams within, acell sector that is served by the antenna structure 900.

A side view of the antenna structure 900 is depicted in FIG. 10. Notethat the lower antenna panel 904 is angled with respect to the verticalaxis of the support 906, such that the forward face 912 (on which theantenna elements 910 are mounted) face slightly downwardly (at anangle). In the example of FIG. 10, the upper antenna panel 902 isgenerally parallel to the vertical axis of the support 906. In otherimplementations, other arrangement of the upper and lower antenna panels902 and 904 can be provided. In yet another implementation, more thantwo antenna panels can be used.

In one exemplary implementation, the antenna elements 908 of the upperantenna panel 902 can be used for forming beams to cover the outer cellregion as well as to communicate with adjacent base stations in theneighboring cells. The lower antenna panel 904 can be used to formlow-power beams for a given cell sector, as well as possibly ahigh-power beam to cover up to the edge of a particular cell sector.

The information that is communicated in beams between base stations indifferent cells includes backhaul information and coordinationinformation. The coordination information can be used to coordinatehandover of mobile stations between different cells. The coordinationinformation can also enable coordination of sweep patterns and sweepdurations in different cells to reduce inter-cell/inter-sectorinterference, and to support network-based MIMO.

“Backhaul” information refers to control and data typically communicatedover a backhaul connection between a base station and a wireless networkcontroller (e.g., packet data serving node, serving gateway, etc.). Anissue associated with wireless communications networks is that the sizesof cells can be relatively small, particularly in densely populatedareas such as urban areas. Another reason for small cell sizes can berequirements for high data rates or high carrier frequencies. Withsmaller cell sizes, a larger number of cells (and thus correspondingbase stations) are present. Each base station typically has to beconnected by a backhaul network to a wireless network controller. Alarge number of basestations means that a corresponding large number ofbackhaul connections would have to be provided. Backhaul connections canbe expensive to deploy, and providing a relatively large number of suchbackhaul connections in a wireless communications network can increasethe costs for a wireless network operator,

In accordance with some preferred embodiments, to reduce the number ofbackhaul connections that would have to be deployed, the antennastructures of base stations can form beams (referred to as “backhaulbeams”) used to carry backhaul information. For example, in FIGS. 9-10,a beam of the upper antenna panel 902 can be employed for the purpose ofcommunicating the backhaul information to another base station that maybe connected by a backhaul connection to the wireless networkcontroller. In general, a subset of base stations in a wireless networkcan be deployed with backhaul connections to a wireless networkcontroller. The remaining base stations are not deployed with backhaulconnections—rather, such base stations communicate backhaul informationover beams to corresponding base station(s) deployed with a backhaulconnection.

FIG. 11 shows two antenna structures 900A and 900B located in twodifferent corresponding cells. In the configuration of FIG. 11, there isno overlap of coverage zones between the upper and lower antenna panels902A, 904A (and 902B and 904B). A backhaul beam can be formed betweenupper antenna panels 902A and 902B of the two antenna structures 900Aand 900B, respectively. Each of the lower antenna panels 904A and 904Bare used to form beams for coverage within respective cell.

FIG. 12 shows a configuration in which there is an overlap of coverageby an upper panel beam and lower panel beam. In this manner, the twopanels can provide MIMO in the outer cell region, where the multipleoutput antennas include some combination of antennas from the upper andlower panels. The multiple output antennas of the upper panel and lowerpanel together can thus provide for increased diversity gain,multiplexing gain, and/or array gain.

Various other configurations are also possible. For example, atdifferent times, the upper and lower antenna panels can be used toprovide different coverage over the cell sector at different timeintervals. For example, in one time period, the lower panel can be usedto cover the entire cell. In another time period, the upper panel can beused to cover just the outer cell region, as well as to provide abackhaul beam. In yet another time period, both the lower and upperpanels can be used cover the outer cell region. In yet anotherconfiguration, in a first time period, the lower panel can be used tocover the inner cell region, while the upper antenna panel is used toprovide the backhaul beam. In a different time period, both the lowerand upper antenna panels are used to cover the inner cell region.

Depending on the desired configuration, the upper and lower antennapanels can be placed close together or far apart. Also, the two antennapanels can use antenna elements having different antenna polarizations.The two antenna panels can operate independently or cooperatively. Thetwo antenna panels can transmit in a time division multiplex manner orsimultaneously. Alternatively, the two antenna panels can be transmittedin a frequency domain multiplex (FDM) manner or at the same frequency.

Moreover, if there is coordination between the upper and lower antennapanels, a handoff of a mobile station is possible from a lower panelbeam to an upper panel beam or vice versa. Note also that with use ofupper and lower antenna panels, power levels of all beams for cellcoverage formed by the antenna elements of the upper and lower panelscan be at the same power level. In such configuration, the coverage ofthe inner cell region versus outer cell region (ring-based coverage) canbe accomplished by orienting the upper and lower panels differently(e.g., the lower panel can be angled downwardly to cover the inner cellregion, while the upper panel is not angled to cover the outer cellregion.

FIG. 13 shows, for a particular beam position within a cell sector,multiple time intervals 800A, 800B, 800C, and 800D. Low-power beams aretransmitted in time intervals 800A, 800B, and 800D, and a high-powerbeam is transmitted in time interval 800C. As depicted in FIG. 13, alow-power beam, such as the low-power beam in time interval 800B, can beused to transmit user data and control signals, as represented by 822.On the other hand, the high-power beam in time interval 800C can be usedto transmit user data and control signals, as well as other controlinformation, such as broadcast overhead channels and pre-flash messages.Broadcast overhead channels can include a system acquisition channelcontaining time and frequency synchronization information, as well ascell, sector, or beam identifier information; and a system broadcastoverhead channel, that can carry system parameters such as beam sweeppatterns, and so forth.

In an alternative implementation, in addition to low-power beams and ahigh-power beam transmitted in time intervals 800A, 800B, 800C, and800D, another time interval 800E (FIG. 14) can be allocated to transmitan omni-directional overhead channel. An omni-directional transmissionmeans that the overhead channel is broadcast in all directions of aparticular cell sector (or cell). If omni-directional transmission isused, there can be time, space, or frequency coordination amongtransmissions of the omni-directional overhead channels by differentbase stations to enhance better signal reception at the mobile station(and to reduce interference between different cells).

In some implementations, OSTMA may be applied to the forward link, butnot to the reverse link. In such implementation, if the cell size isdesigned based on the reach of the forward link, then the forward linkmay have a further reach (due to presence of the high-power beam) than amobile station would have in the reverse link. To address this issue, arelaying feature (referred to as “ad hoc relay”) can be provided inmobile stations within a cell sector, where one mobile station is ableto listen to another mobile station and to relay the information of theother mobile station to the base station. For example, a first mobilestation can be located near the edge of a particular cell sector, whilea second mobile station is located closer to the base station. In thisscenario, information transmitted in the reverse link by the firstmobile station can be relayed by the second mobile station to the basestation. Without the relay, the transmission from the first mobilestation may not be able to reliably reach the base station.

To transmit reverse link information from the first mobile station tothe second mobile station for ad hoc relay as discussed above, in a timedivision duplexing (TDD) system, an unused forward link time slot can bereused for relaying reverse information from the first mobile station tothe second mobile station in the reverse link direction.

Also, for more robust communication of control channels when the cellsize is designed based on the forward link reach, the mobile station cantransmit traffic data to just one base station, but can transmit controlchannels to multiple base stations using ad hoc relay to ensure thatcontrol channels reach the intended serving base station.

Another issue associated with designing cell sizes based on forward linkreach is that reverse link control message ACK may be slow in gettingback to the base station due to the ad hoc relay as discussed above. Toaddress this issue, the base station can simply transmit bursts oftraffic data without waiting for responsive acknowledgments.

Alternatively, the cell size can be designed based on the reach of thereverse link, in which case cell sizes would be smaller. In such animplementation, a base station can reach multiple cells in the forwardlink; as a result, it may be possible that the serving cell sector forthe forward link is different from the serving cell sector for thereverse link. For example, base station A in cell A can be the forwardlink serving base station, whereas base station B in cell B is thereverse link serving base station. Base station A can reach both cell Aand cell B, but a mobile station in cell B can only reach base stationB. In this scenario, certain reverse control messages, such as CQImessages or reverse acknowledgment (RACK) messages, can be sent on thereverse link from the mobile station to base station B, which thenrelays the control messages to base station A (which is the forward linkserving base station).

It is noted that certain types of control information may have to bedelivered to all mobile stations in all directions. However, since thehigh-power beam covers just one beam position in any give time interval,the high-power beam cannot be used to transmit such control informationto all mobile stations. To address this, such control information can betransmitted by the base station in low-power beams with low code rates(which enables a higher probability decoding of such control informationby mobile stations located near the cell edge). Examples of controlinformation that may have to be delivered to all mobile stations in alldirections include a forward link acknowledgment channel (to provideacknowledgments to mobile stations) and forward link power controlchannel (to provide power control messages to mobile stations).

If a dynamic sweep pattern and/or dynamic beam duration is used, whichmay mean that beam identifiers would have to be provided to mobilestations, the base station can also use low-power beams with low coderates to deliver the beam identifiers to mobile stations located nearthe cell edge. The beam identifier allows a mobile station to know whichnext beam will be turned on.

It is noted that in some embodiments, an OSTMA subsystem can beintegrated with a non-OSTMA system. A non-OSTMA system does not employthe OSTMA techniques discussed above.

In this scenario, interleaving of OSTMA data and non-OSTMA data can beperformed over a wireless link. For example, as depicted in FIG. 15,OSTMA superframes 950 are transmitted during an interval associated withOSTMA operation, whereas non-OSTMA superframes 952 are transmittedoutside the time periods of OSTMA operation. A “superframe” refers to aframe structure that contains other frames. More generally, reference ismade to a “frame,” which is a collection of data that is sent over awireless link.

In an alternative embodiment, as depicted in FIG. 16, a superframe 960can include non-OSTMA data interlaced with OSTMA data. The beginning ofthe superframe 910 can include an omni-broadcast preamble 954 toindicate positions of non-OSTMA data and OSTMA data. In alternativeimplementations, other frame structures can be used.

Exemplary components of a base station 1000 and mobile station 1002 aredepicted in FIG. 17. The base station 1000 includes a wireless interface1004 to communicate wirelessly over a wireless link with a wirelessinterface 1006 in the mobile station 1002. The base station 1000includes software 1008. That is executable on one or more centralprocessing units (CPUs) 1010 in the base station 1000 to perform tasksof the base station. The CPU(s) 1010 is (are) connected to a memory1012. The software 1008 can include a scheduler and other softwaremodules. The base station 1000 also includes an inter-base stationinterface 1014 to communicate information with another base station,such as backhaul information and/or coordination information.

Similarly, the mobile station 1002 includes software 1016 executable onone or more CPUs 1018 connected to a memory 1020. The software 1016 isexecutable to perform tasks of the mobile station 1002. Instructions ofsuch software (1008 and 1016) can be loaded for execution onto the CPUsor other types of processors. The processor can include amicroprocessor, microcontroller, processor module or subsystem(including one or more microprocessors or microcontrollers), or othercontrol or computing devices. A “processor” can refer to a singlecomponent or to plural components.

Data and instructions (of the software) are stored in respective storagedevices, which are implemented as one or more computer-readable orcomputer-usable storage media. The storage media include different formsof memory including semiconductor memory devices such as dynamic orstatic random access memories (DRAMs or SRAMs), erasable andprogrammable read-only memories (EPROMs), electrically erasable andprogrammable read-only memories (ERPROMs) and flash memories; magneticdisks such as fixed, floppy and removable disks; other magnetic mediaincluding tape; and optical media such as compact disks (CDs) or digitalvideo disks (DVDs).

As a further embodiment of the present invention, the channel qualityindicator (CQI) is used to support the transmissions, with the CQI beingestimated based on a pilot channel indicator signal that is periodicallybroadcast on the forward link in the PHY frame signaling structure. Thisembodiment can apply to both multiplexing modes 1 and 2 in the UMBstandard for OSTMA systems. Specifically, the CQI is estimated from theF-CPICH common pilot indicator channel signaling for multiplexing mode 1and DRCH distribution resources zone in multiplexer mode 2, oralternatively from the F-CQIPICH pilot indicator channel signaling inBRCH block resource channel zone of multiplexer mode 2. The F-CPICH orF-CQIPICH pilot indicator channel signaling is beamformed, with onesignal per beam, and the F-CPICH or F-CQIPICH pilot indicator channelsignaling are transmitted at high powers to make sure cell-edge user seethe pilot indicator channel signal from all the beams. The SISO or MIMOtransmission protocol is used in each beam for this pilot indicatorchannel signaling, and an example of the PHY frame using the F-CPICHpilot indicator signaling is shown in FIG. 18. The F-CPICH of beampositions 1, 2, 3, and 4 are indicated by the blocks at 180 shown to beperiodically broadcast in the indicated time frames.

In this embodiment, the mobile station 1002 would receive the F-CPICH orF-CQIPICH pilot indicator channel signaling as received from allbeamformed transmissions. The mobile station 1002 would determine whichbeam position corresponds to the high-power beam based on the F-CPICH orF-CQIPICH pilot indicator channel signaling, and the mobile station 1002would estimate the CQI value from the F-CPICH or F-CQIPICH pilotindicator channel signaling. The mobile station 1002 can also bereferred to as an access terminal. The CQI would be estimated and a beamindex would be calculated to provide information on the beam position.

The mobile station 1002 would provide feedback to the basestation 1000in two modes. In the first mode, the mobile station 1002 would feed backthe highest CQI value and its corresponding beam position via a beamindex (e.g. beam position 1, 2, 3 or 4 in a four beam sector) to thebasestation 1000. In the second mode, the mobile station 1002 would feedback the highest two CQI values and two corresponding beam positions viaa beam index (e.g. beam position 1 and 2, 2 and 3, etc. in a four beamsector) to the basestation 1000 if the mobile station 1002 determinesthat it is located in the service area of two overlapping beams. Themobile station 1002 initiates a Layer 3 signaling to trigger the switchbetween the two modes of providing feedback.

In response to this feedback, the basestation 1000 will schedulecommunications to be transmitted to the mobile station 1002 based on thebeam position index and the CQI value. In the second mode, thebasestation 1000 will schedule users so that the high-power beam willnot create strong interference to users in the neighboring low-powerbeams. If the mobile station 1002 is located in the middle of two beams,the basestation 1000 can schedule data transmissions on both overlappingbeams. The data on these overlapping beams will occupy the same resourcelocation, and the data will be processed through the same scramblingprotocols for both beams. The mobile station 1002 located in theoverlapping beam areas will receive the transmissions and monitor theF-SCCH parameter value on the beam position having the highest valueCQI, and one bit in the FSCCH parameter will designate the redundantdata transmission on two overlapping beam positions.

From the CQI value and/or the beam index information, the basestation1000 or the mobile station 1002 will determine whether the mobilestation 1002 is being served by a high-power or low-power beam. If thebasestation 1000 makes that determination, the mobile station 1002 willneed to monitor the F-SCCH parameter value for beam position with thehighest CQI value for both the high and low power beams.

This approach gives the basestation 1000 more flexibility in schedulingon both high and low power beams, as high power beams can also servecell-center users. If the mobile station 1002 makes that determination,the mobile station 1002 will feed back a signal bit in a transmission toindicate the choice of low or high power beam or a channel qualityindicator (CQI) corresponding to the high power beam and/or beam indexinformation. In this embodiment, significant power savings can beachieved by having the mobile station 1002 monitor the F-SCCH parametervalue of the beam position with the highest CQI value for either high orlow power beams, especially for cell-edge users. The reported CQI willbe adjusted for future transmissions if the mobile station 1002 isserved by a low-power beam.

The pilot channel indicators for the CQI measurement can also betransmitted in the high beam only, while the low-power beam transmits adifferent type of pilot signal for demodulation purposes. In thisembodiment, the CQI is only reported when the user receives thehigh-power beam, or when the estimated CQI exceeds a minimum thresholdvalue. Based on the knowledge of the beam sweeping pattern ascommunicated by the basestation 1000, the user would know about thetiming associated with high beam transmission in the sector. The beamindex may not be fed back to the basestation 1000 with the CQI index, asthe basestation 1000 may derive the beam coverage for the user based onthe quality of the beam transmission and the timing associated with theCQI feedback.

In another embodiment, a forward link (FL) control channel signal istransmitted using different signals and methods, which assists with thelocation of the best suited beam for transmissions with the mobilestation 1002. In one approach, the DRCH distribution resource zonesignal in multiplexer mode 2 will transmit the FL control signals.Because of the limited number of users in each beam, a single ormultiple DRCH signals could be used per beam to control signaling. Thecontrol DRCH signal could be transitioned to hop randomly around thesector to minimize collisions with neighboring beams. The controlchannel in the low-power beam will be on low-power, and the controlchannel in the high-power beam will be on high power.

In a second approach, the FL control channel signal is transmitted usingthe F-SCCH parameter, and access grant is sent in the high power beam.The mobile station 1002 monitors the F-SCCH parameter value for thehigh-power beam designation. In a third approach, the F-ACKCH parameteris used to transmit the FL control channel signal. In this approach, afew tones of the ACK signal are transmitted in high power on the lowpower beam so the cell-edge users can be reached.

In a fourth approach, the F-PCCH and F-PQICH signals can be used to sendthe FL control channel signal, and those signals may be sent on thehigh-beam position corresponding to the location of the mobile station1002. The transmission may be adjusted if the mobile station 1002 movesfrom one beam position to another beam position. In the Ultra MobileBroadband protocol, the F-PCCH is typically sent every eight frames andthe F-PQICH is sent every 16 frames.

In a fifth approach, the F-FOSICH and F-IOTCH signals can be used tosend the FL control signal. These signals may be transmitted by thehigh-power beam and the mobile station 1002 receives these F-FOSICH andF-IOTCH signals every four frames. Or, in the alternative, these signalsmay be transmitted by all beams and allows a few tones of the FOSICH andIOTCH signals to be transmitted in high power in the low power beam sothe cell-edge users can be reached. In the Ultra Mobile Broadbandprotocol, the F-FOSICH is typically broadcast in every frame, and theF-IOTCH can be broadcast as fast as every frame.

In the foregoing description, numerous details are set forth to providean understanding of the present invention. However, it will beunderstood by those skilled in the art that the present invention may bepracticed without these details. While the invention has been disclosedwith respect to a limited number of embodiments, those skilled in theart will appreciate numerous modifications and variations therefrom. Itis intended that the appended claims cover such modifications andvariations as fall within the true spirit and scope of the invention.

What is claimed is:
 1. A method for operating a receiver, the methodcomprising: by the receiver: receiving pilot channel indicator signalsfrom an access node corresponding to a plurality of spatial beams,wherein each of the pilot channel indicator signals is transmitted in abeamformed fashion on one of the plurality of spatial beams; exchanginglayer 3 signaling, wherein the layer 3 signaling indicates a feedbackmode; generating a feedback signal based on the layer 3 signaling,wherein: when the feedback mode is a first mode, said feedback signalincludes a first beam index, wherein the first beam index corresponds tothe pilot channel indicator signal of the first beam among the pluralityof spatial beams; and when the feedback mode is a second mode, saidfeedback signal includes two beam indices corresponding to two pilotchannel indicator signals of two spatial beams among the plurality ofspatial beams, wherein the second mode facilitates transmission to thereceiver on the two spatial beams simultaneously; transmitting saidfeedback signal to the access node from the first receiver; receiving atransmission from the access node, the transmission at least in partbased on an analysis of the feedback signal.
 2. The method of claim 1,wherein said receiving the transmission from the access nodes comprisesreceiving the transmission on only one of the plurality of spatialbeams.
 3. The method of claim 1, wherein said receiving the transmissionfrom the access nodes comprises receiving the transmission on the twospatial beams of the plurality of spatial beams.
 4. The method of claim3, wherein the transmission on the two spatial beams of the plurality ofspatial beams is a single set of data transmitted from both beams in thesame resource location.
 5. The method of claim 1, wherein, in the secondmode, a control channel received from the access node comprises anindication that the transmission is on two spatial beams.
 6. The methodof claim 1, wherein a control channel is received over one or more ofthe spatial beams.
 7. The method of claim 1, wherein the plurality ofspatial beams are transmitted using an antenna panel of the access node,and wherein the antenna panel comprises antenna elements of differentpolarizations.
 8. An apparatus, comprising: one or more processors,wherein the one or more processors are configured to cause a receiverto: receive pilot channel indicator signals from an access nodecorresponding to a plurality of spatial beams, wherein each of the pilotchannel indicator signals is transmitted in a beamformed fashion on oneof the plurality of spatial beams; generate a feedback signal based onlayer 3 signaling, wherein the layer 3 signaling indicates a feedbackmode, wherein: when the feedback mode is a first mode, said feedbacksignal includes a first beam index, wherein the first beam indexcorresponds to the pilot channel indicator signal of the first beamamong the plurality of spatial beams; and when the feedback mode is asecond mode, said feedback signal includes two beam indicescorresponding to two pilot channel indicator signals of two spatialbeams among the plurality of spatial beams, wherein the second modefacilitates transmission to the receiver on the two spatial beamssimultaneously; transmit said feedback signal to the access node fromthe first receiver; receive a transmission from the access node, thetransmission at least in part based on an analysis of the feedbacksignal.
 9. The apparatus of claim 8, wherein said receiving thetransmission from the access nodes comprises receiving the transmissionon only one of the plurality of spatial beams.
 10. The apparatus ofclaim 8, wherein said receiving the transmission from the access nodescomprises receiving the transmission on the two spatial beams of theplurality of spatial beams.
 11. The apparatus of claim 8, wherein thetransmission on the two spatial beams of the plurality of spatial beamsis a single set of data transmitted from both beams in the same resourcelocation.
 12. The apparatus of claim 8, wherein, in the second mode, acontrol channel received from the access node comprises an indicationthat the transmission is on two spatial beams.
 13. The apparatus ofclaim 8, wherein a control channel is received over one or more of thespatial beams.
 14. The apparatus of claim 8, wherein the plurality ofspatial beams are transmitted using an antenna panel of the access node,and wherein the antenna panel comprises antenna elements of differentpolarizations.
 15. A non-transitory computer accessible memory mediumstoring program instructions executable by a processor to: receive pilotchannel indicator signals from an access node corresponding to aplurality of spatial beams, wherein each of the pilot channel indicatorsignals is transmitted in a beamformed fashion on one of the pluralityof spatial beams; generate a feedback signal based on layer 3 signaling,wherein the layer 3 signaling indicates a feedback mode, wherein: whenthe feedback mode is a first mode, said feedback signal includes a firstbeam index, wherein the first beam index corresponds to the pilotchannel indicator signal of the first beam among the plurality ofspatial beams; and when the feedback mode is a second mode, saidfeedback signal includes two beam indices corresponding to two pilotchannel indicator signals of two spatial beams among the plurality ofspatial beams, wherein the second mode facilitates transmission to thereceiver on the two spatial beams simultaneously; transmit said feedbacksignal to the access node from the first receiver; receive atransmission from the access node, the transmission at least in partbased on an analysis of the feedback signal.
 16. The non-transitorycomputer accessible memory medium of claim 15, wherein said receivingthe transmission from the access nodes comprises receiving thetransmission on only one of the plurality of spatial beams.
 17. Thenon-transitory computer accessible memory medium of claim 15, whereinsaid receiving the transmission from the access nodes comprisesreceiving the transmission on the two spatial beams of the plurality ofspatial beams.
 18. The non-transitory computer accessible memory mediumof claim 15, wherein the transmission on the two spatial beams of theplurality of spatial beams is a single set of data transmitted from bothbeams in the same resource location.
 19. The non-transitory computeraccessible memory medium of claim 15, wherein, in the second mode, acontrol channel received from the access node comprises an indicationthat the transmission is on two spatial beams.
 20. The non-transitorycomputer accessible memory medium of claim 15, wherein a control channelis received over one or more of the spatial beams.